The present invention relates to write strategy tuning of an optical storage device, and more particularly, to method and system for tuning write strategy parameters utilizing data-to-clock edge deviations.
As multimedia application technology continues to progress, the demand for storing massive digital data rapidly increases. As a result, high storage volume and compact size optical storage media such as Compact Discs (CDs) or Digital Versatile Discs (DVDs) have become highly popular, and optical storage devices such as CD drives or DVD drives have become standard accessories of personal computers, utilized for performing the multimedia applications.
Take the CD drive as an example. When the CD drive is controlled to write data to a CD-Rewritable (CD-RW) disc, the writing power of a laser diode in the CD drive is usually set to be a specific value, and write pulses corresponding to the data are utilized for forming pits and lands onto the grooves of the CD-RW disc. The specific value of the writing power can be derived from an optimal power calibration (OPC) process. Through a write strategy tuning process, which is also referred to as a recording strategy tuning process, changing write strategy parameters for controlling widths of the write pulses increases the accuracy of lengths of pits and lands formed on the CD-RW disc.
According to the related art, a specific device such as an oscilloscope can be utilized during the write strategy tuning process. Usually, according to an eye pattern of a plurality of reproduced waveforms shown on the oscilloscope after an advance trial writing process, a new set of write strategy parameters for controlling the widths of the write pulses are determined, based on experience, by an engineer or researcher. Utilizing this method takes a lot of time because the same process must be repeatedly performed for various applicable media and different recording speeds. The write strategy tuning process at least includes writing test data, inspecting an eye pattern of reproduced waveforms shown on the oscilloscope, and determining a new set of write strategy parameters by experience according to the eye pattern. The write strategy tuning process mentioned above is time consuming since determining the write strategy parameters by inspecting eye patterns is not an automatic operation. In addition, the write strategy tuning process mentioned above is indefinite since determining a new set of write strategy parameters according to the eye pattern is not quantitative. Under certain situations, an unclear eye pattern would invalidate or interfere with the write strategy tuning process.
A specific instrument such as a time interval analyzer (TIA) or a jitter meter could be helpful for the purpose of deriving information for determining a new set of write strategy parameters. However, similar routine work is still required, and if the TIA or jitter meter is simply coupled for measuring without an additional control system being set up, the same drawbacks caused by the manual tuning process will still exist. In addition, the information derived from the specific instrument is usually implicit and therefore the process still takes a large amount of time.
According to the related art, pattern dependency such as relationships between pit lengths and land lengths can be utilized in a write strategy tuning process. However, deriving the pattern dependency requires lots of calculations.